1. Field of the Invention:
This invention relates to evaporative cooling systems and, more particularly, to water distribution apparatus for an evaporative cooling system.
2. Description of the Prior Art:
In relatively hot, relatively dry areas, evaporative cooling systems are popular for their relatively low cost of acquisition and operation. Basically, evaporative cooling systems include a medium which is saturated with water and through which hot air is drawn by a blower. The air passing through the water saturated cooling medium gives up heat of evaporization in evaporating the water from the medium. The air thus cooled is then distributed for cooling purposes.
Early evaporative cooling systems, and typical contemporary evaporative cooling systems, utilize a small pump to circulate water over the cooling medium. The pump is operational during the times that the blower is also operational. Water is thus constantly recirculated. A float controlled valve system connected to a water source replenishes water lost by evaporation.
In efforts to save water, or to conserve water, systems have been suggested for limiting the amount of water flowing over the medium. By doing this, the requirement of the recirculating pump may be eliminated. Moreover, water is saved since only an amount of water sufficient to keep the medium relatively well saturated is required.
In addition, by eliminating the recirculation of the water, there is minimum salt (mineral) accumulation on the medium. The salt accumulation on the medium decreases the efficiency of the medium as time progresses. Even with the bleeder circuits of the past several years, there is still a substantial amount of highly mineralized recirculated water which deposits excess salts on the medium.
Prior art attempts for optimizing the use of the water with respect to the cooling medium by providing only the amount of water to keep the medium saturated or wetted has been directed toward non-recirculating systems controlled by straight timer circuits. That is, a timer circuit will turn on a water supply system for a specific amount of time, and then the circuit turns off, stopping the water flow. The timer has both predetermined "on" times and predetermined "off" times. For example, a typical timer situation may be to turn on to provide water for one minute and then to go off for one minute.
Obviously, such predetermined, fixed time systems cannot take into consideration the actual evaporation of the water from the medium, and thus may either allow the cooling medium to dry out or may supply excess water to the medium. The timer system cannot be affected by changes in the evaporation rate due to air volume, air velocity, or the condition of the evaporative medium.
Moreover, the timer system is not able to take into consideration fluctuations in water pressure. If the water pressure is high, an excess amount of water may be provided. If water pressure is low, then the medium may only become marginally wetted.
The apparatus of the present invention overcomes the problems of the prior art by utilizing a float activated switch system combined with calibrated orifices in a catch pan to allow water to drain at a predetermined rate from the pan. The amount of water in the pan, and flowing out of the pan through calibrated orifices, determines the on time and off time of the water supply system.